*Ace* You poor poor man. You do not seem really understand what you are trying to do here.... and judging by this topic so far... neither does anyone else...
Next time you post a question, how about being a wee bit more specific about your power setup?
I *think* you trying to:
Externally bridge two Orion 1200D amps to a single H2 subwoofer.. and now you want to do it *twice.*
While I fancy myself a car-stereo expert, as DYohn and heamphyst (hemp-fist? what does that mean anyway?) will attest, I'm far from, and I really have no clue how those amps "externally bridge" themselves so I'm just going to assume that you are running the 1-ohm load from each amp, for a full 1200 watts to each voice coil of a DVC 2-ohm H2. (again, I have absolutely no idea how "externally bridging" something works or what the wiring looks like, but given the behavior you describe I think I'm prolly right..)
So as it stands, you are asking a round 2400 watts from your amps.. and that is *output* nevermind the extra 30% or so in amplifier efficency you are going to lose. So lets assume you are asking about 3000 watts from your power system, all 3 caps, and all. By the way, the capacitors, despite what most ppl on this board will tell you, are not at all useless.. but when you are as power deficient as you are..they might as well be...
Plugging this into Ohms law we get amps=watts/volts....
or 240 = 3000/12.5
Jag or not *no* OEM alt makes anywhere near 240 amps. Not only does *no* OEM alt make anything near that *no* OEM battery will take that kind of draw for long...
Batteries are kinda strange things.. car batteries especially... you probably fried you battery almost immediately with those amps... yet... you still could get 12.5 - 14.4 V out of it.. enough to start it and roll the nice windows down...but under any load what-so-ever the thing immediately gives out.. which is why your caps are good for *one or two thumps* I'd put 10-1 your battery is bad, whether or not it starts your car..
If you are not going to consider a HO alt, here is the *reality* of your situation:
1) Scrap the idea of new amps. Not only is that a stupid waste of money, you will never ever ever get any use out of them as your power draw will now jump to something on the order of 400 - amps and that is hard for even the beefiest of batteries and all the capacitors you care to shake a stick at to keep up with. 400-amps, my friend, will run an electric chair that woulda put Mickey Rourke down *the first time* (...anyone?)
2)4-gauge is totally under-rated for what you want. You shouldn't have a scrap of power wire in your entire system, regardless of your battery, alt, or cap setup, less than 2-gauge running around at all. Lots and lots of 2-gauge. (Or 0/1 (or is it 1/0?) gauge, I think 2-gauge is rated to like 220-amps) The *only* 4-gauge in your system should be running off of the distro block straight to your amps. Each is grounded with 4-gauge as well.
3)For the amps you already have, let alone the ones you should not add, you need *at least* a pair of deep cycles in parallel. You need to wire these to a 200-amp RELAY. When ever you turn the key to "ACC" these batteries connect in PARALLEL, when you turn the car off, they disconnect. If you can afford an X-type, I dunno why you couldn't afford two Yellow Tops. Buy two of whatever fits under your hood.
4)Even if I'm totally wrong, and you only need half that much power from your amps, you still are asking *quite* a load. 120 - 150 amps is a tremendous drain on a stock charging system... again, Jag or not. The 'two batteries' suggestion should still be applied.
5)As power deficient as you are, all the capacitors in the world are not going to help... you need *massive* storage capacity, not voltage stiffening...
240 amps is sick man.
Sick.
"I'm finished!" - Daniel Plainview